Gas flow regulators are used to provide a medical gas, such as oxygen, to a patient from a source supply of the gas. The gas is normally stored in a cylinder or supply vessel under high pressure. The gas flow regulator reduces the high pressure (about 500–3000 psi) to a lower pressure (about 50 p.s.i.) and provides the gas at a metered flow rate, measured in liters/minute. It is desirable to manufacture gas flow regulators as a compact, light weight and smooth to the touch package. It is also desirable to color code the devices to indicate the gas being handled (e.g., green for oxygen) or the preference of the owner of the device.
In the prior art, compact gas flow regulators are generally constructed in either a one-piece or two-piece aluminum alloy housing. In one-piece regulators, a pressure reducing element and flow control subassembly is typically held into the housing using a c-clip or snap ring. In these devices, the c-clips do not offer adequate stability. In addition, the flow control knob is usually snapped into place and can, therefore, accidentally separate from the regulator.
In two-piece regulators, a pressure reducing element and a piston are disposed within the yoke housing and a flow control housing, having a flow control element therein, screws together with the yoke housing. Consequently, the two-piece regulators have a characteristic division line between the yoke housing and the flow control housing. The use of two pieces also results in additional cosmetic problems. For example, it can be difficult to uniformly color the two housings due to variations in anodizing the pieces. Although two-piece regulators have a less desirable cosmetic appearance than one-piece regulators, the threaded attachment provides certain durability advantages.